He finished this season ranked 33, but as Quinten Hann did not participate in any events, Day was always among the top 32 seeds, meaning one less qualifying match than he would otherwise have faced.

After failing to progress past the last 16 in the next three tournaments, he reached the semi-finals of the China Open, beating Matthew Stevens, Ken Doherty and Mark Williams before he was beaten by Stephen Maguire 5–6, denying him a place in the final.

Day reached the final of the 2008 Grand Prix where he lost to John Higgins, defeating Ricky Walden, Mark Selby, Jamie Cope and Ali Carter.

A disappointing 2009–10 season in which he reached only one quarter-final (in the Welsh Open), culminated in an 8–10 first round defeat in the World Championship to Mark Davis.

[9] There he beat fellow qualifier Cao Yupeng 13–7 and held a 5–2 lead in the early stages of his quarter-final match against compatriot Matthew Stevens.

[12] He beat Ding Junhui 6–4 in a high quality first round encounter,[13] before letting a 3–0 lead against world number two Mark Selby slip to lose 4–6.

[14] Day played in nine of the ten minor-ranking Players Tour Championship events during the season with his best results being two quarter-final defeats to be ranked 32nd on the Order of Merit, just outside the top 26 who qualified for the Finals.

[15] Day struggled in the second half of the season as he failed to qualify for four of the remaining five ranking events, losing 2–5 in the first round of the World Open to Mark Allen in the one he did reach.

[18] He went a stage further at the German Masters and, in an attempt to play in his first ranking final since 2008, he came from 3–5 down against Ding Junhui to level the match, but lost the deciding frame.

[20] His season then ended when he lost 7–13 to Judd Trump, but he did increase his ranking by 10 places to world number 21, his highest finish for four years.

After Day won the final two frames of his first round match against world number one Ding Junhui at the German Masters to eliminate him 5–4, he said that he was working on his consistency to get back into the highest echelons of the game.

[24] He then beat Alfie Burden 5–2 to face Liang Wenbo in Day's only quarter-final appearance of the season and was narrowly beaten 5–4.

[25] In Day's home event, he suffered a surprise 1–4 loss to amateur Oliver Brown in the second round of the Welsh Open.

[27] Day lost 4–5 to Ding Junhui in the second round of the Shanghai Masters, but turned the tables at the same stage of the International Championship by beating him 6–5.

[30] He lost 2–6 to Dechawat Poomjaeng in the second round of the UK Championship, but knocked out reigning world champion Stuart Bingham 5–3 to reach the quarter-finals of the German Masters.

[31] He made two centuries and won the deciding frame on the final black against John Higgins to make another quarter-final at the World Grand Prix.

[33] After being defeated 3–10 by Higgins in the opening round of the World Championship, Day said he would be working on his fitness in the off season in an attempt to improve his concentration during matches.

[34] Day advanced to the quarter-final stage of the Shanghai Masters by overcoming Neil Robertson and Mei Xiwen, both 5–2, before losing 3–5 to Mark Selby.

[41] Day was a seeded player for the World Championship, but lost 4–10 Xiao Guodong in the first round and once again blamed his lack of concentration for the early exit.